89 Campfire Science-Mid

Campfire Science FOCUS Question Why do people use campfires?

Why We Make Campfires Thousands of years ago, people made campfires. Fires protected people from predators and biting insects. They made people feel safe. The flames kept people warm and cooked raw meat. The light helped people locate family and friends in the dark. Today, electricity helps people do many of these things. People live in warm houses for protection. Electricity lights up the night. Stoves and microwaves heat food. And people connect with each other using cell phones and computers. But people still enjoy campfires. When people go camping they use fire to cook their food and keep warm. A campfire is still a good spot for friends and family to gather and tell stories.

Giving Off Energy Campfire wood has stored energy called potential energy. This type of energy is ready to be used but hasn't been yet. A ball near the edge of a table also has stored energy. It is ready to roll off but is not moving yet. The potential energy in firewood is called chemical energy. The energy in the wood is stored in its molecules. Energy itself cannot be created or destroyed. It can only change from one kind to another. When wood burns, its potential energy turns into two other kinds of energy. The change from one kind of energy to another is called a conversion (kun-VER-zhun). A conversion of energy happens when fire turns wood to ash.

Light and Heat Some of the potential energy in the wood is converted to light energy. That's why a fire glows! Light energy can help us feel safe on a dark night. The other type of converted energy. given off when wood burns is heat. A fire's heat is called thermal energy. This kind of energy can keep us warm and cook our food. The heat energy created by a burning campfire dissipates, or spreads out, as the fire burns. The heat warms the cool air around the fire. After a campfire has burned, the wood's chemical energy has been released, and the wood has turned to ashes.

Campfire Cooking People use campfire energy to cook food through convection—the movement of heat through the air. People put marshmallows and hot dogs on sticks and hold them over a campfire. The heat energy cooks the food from a distance. Another way to cook food is through conduction. People wrap baked potatoes or kabobs in foil and place them directly into the fire's hot embers. The heat transfers directly to the food. Cooking changes the taste and texture of food. These are chemical changes that cannot be reversed.

Getting Ready Safety is very important when building a campfire, and you should always have an adult's help. In an open, outdoor place, clear out a large area of all leaves and sticks. Then place rocks in a big circle within the clear area to construct a fire ring. Next, collect fuel for the campfire. Thin brittle fuels such as dried grass, pine needles, and bark are called tinder. Tinder helps get the fire started. Kindling goes on top of the tinder. Kindling is made up of sticks about as thick as a pencil. Finally, place fuelwood—branches and logs—on the top.